The invention relates to a drill head for an at least partially rotationally and percussively driven rock drill, in particular, for boring blasting holes for explosive charges.
Such drill heads set with cutting edges made of hard material for rock drills having a diameter of approximately 30 cm are, as wearing parts, detachably connected to the leading end of an at least partially rotationally and percussively driven drilling shaft of several meters length, which conventionally has a hollow flushing channel.
U.S. Pat. No. 6,021,855 discloses a drill head set with cutting edges made of hard material connected axially and freely moveable within a several millimeters limit to a hollow drilling rod, whereby an improved compressive pulse delivery into the rock is achieved.
DE 9308444U1 discloses a drill head connected with a drilling rod by a bayonet connection, wherein the drill head forms two radially projecting driver blades on a guide pilot, which engage in associated connection slots. The partially open axial stop of the connection groove on the drill head side is unusable for a limited axial free moveable drill head.
U.S. Pat. No. 4,043,409 discloses a potlike drill head set with cutting edges made of hard material axially resiliently damped and detachably connected by a bayonet connection with a hollow drilling shaft, wherein the drill shank forms at least two radially projecting driver blades, which engage in associated connection grooves and can be peripherally and axially displaced. Limited free axial movement is not possible due to the resiliently buffered drill head.